I read your fake book review on Mastodon, that was a great idea. Now I want to see your follow-on adventure with the full masquerade!
You could include a few of the ideas you developed in the fake book review in the intro to this adventure (e.g. the bit about the long masquerade thrown by the prince while the king is away on endless war campaigns). The masquerade ball is a nice twist on the dungeon escape, I think it’s worth giving this context.
The intro page is has all the necessary information. Paragraph 1 is great, simple and to the point. I think I would move paragraph 2 to the end of the page, and group the introductory info under, “The Masquerade”, “The Masks” and “Player Intro”, with a natural segue from Player Intro into Location A.
The map is very easy to follow, with an interesting choice of locations. You could make more use of the isometric layout by having more 3D features on the upper level, e.g. towers or battlements around the courtyard, or a balcony in the main castle where the half-eaten waste and torn clothes are thrown down (p.1).
I wondered why the escapees don’t have to pass through the barracks, and why the stairs from the dungeon lead straight into the masks atelier. A slight rearrangement of the rooms would put more obstacles in the way of the players, forcing them to be inventive to escape the dungeon and obtain masks.
Overall this looks like a fun and very playable adventure. Although it’s system neutral, I can see it working well as a zero-level funnel for Dungeon Crawl Classics or gauntlet for Shadowdark.